﻿#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	int arr[9] = { 1,2,3,4,5,1,2,3,4 };
	//规律:a^a=0,a^0=a,a^b^a=b;
	int t = 0;
	for (int i = 0; i < 9; i++)
	{
		t ^= arr[i];
	}
	printf("出现一次的数为:%d", t);
	return 0;
}
